Isamaya has requested a new pin number for her debit card from the bank. It has been sent to her parents house in Cambridge.

Isamaya sends an email to Mike asking him to open the letter and email her the digits.

Isamaya: 
Hey Dad!  Plz can you email the pin when it arrives?
Thanks xxx

Mike:

I've got it - first two as grandad's house number. 

x

Isamaya:

Cheers, please can you just send it all over.

xx

Mike:

grandad's house number, zero and your birthday

Isamaya:

8609?

Mike:

Oh Isamaya! This is what I was trying to avoid!!

Mike:

Grandads number is one higher.